kern_core.c revision 1.33
1 /* $NetBSD: kern_core.c,v 1.33 2020/10/26 17:35:39 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1989, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)kern_sig.c 8.14 (Berkeley) 5/14/95 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: kern_core.c,v 1.33 2020/10/26 17:35:39 christos Exp $"); 41 42 #ifdef _KERNEL_OPT 43 #include "opt_execfmt.h" 44 #include "opt_compat_netbsd32.h" 45 #endif 46 47 #include <sys/param.h> 48 #include <sys/vnode.h> 49 #include <sys/namei.h> 50 #include <sys/acct.h> 51 #include <sys/file.h> 52 #include <sys/stat.h> 53 #include <sys/proc.h> 54 #include <sys/exec.h> 55 #include <sys/filedesc.h> 56 #include <sys/kauth.h> 57 #include <sys/module.h> 58 #include <sys/compat_stub.h> 59 #include <sys/exec_elf.h> 60 61 #ifdef COMPAT_NETBSD32 62 #define COREDUMP_MODULE_DEP "compat_netbsd32_ptrace" 63 #else 64 #define COREDUMP_MODULE_DEP NULL 65 #endif 66 67 MODULE(MODULE_CLASS_MISC, coredump, COREDUMP_MODULE_DEP); 68 69 struct coredump_iostate { 70 struct lwp *io_lwp; 71 struct vnode *io_vp; 72 kauth_cred_t io_cred; 73 off_t io_offset; 74 }; 75 76 static int coredump(struct lwp *, const char *); 77 static int coredump_buildname(struct proc *, char *, const char *, size_t); 78 static int coredump_write(struct coredump_iostate *, enum uio_seg segflg, 79 const void *, size_t); 80 static off_t coredump_offset(struct coredump_iostate *); 81 82 static int 83 coredump_modcmd(modcmd_t cmd, void *arg) 84 { 85 86 switch (cmd) { 87 case MODULE_CMD_INIT: 88 MODULE_HOOK_SET(coredump_hook, coredump); 89 MODULE_HOOK_SET(coredump_write_hook, coredump_write); 90 MODULE_HOOK_SET(coredump_offset_hook, coredump_offset); 91 MODULE_HOOK_SET(coredump_netbsd_hook, real_coredump_netbsd); 92 #ifdef EXEC_ELF32 93 MODULE_HOOK_SET(coredump_elf32_hook, real_coredump_elf32); 94 #endif 95 #ifdef EXEC_ELF64 96 MODULE_HOOK_SET(coredump_elf64_hook, real_coredump_elf64); 97 #endif 98 MODULE_HOOK_SET(uvm_coredump_walkmap_hook, 99 uvm_coredump_walkmap); 100 MODULE_HOOK_SET(uvm_coredump_count_segs_hook, 101 uvm_coredump_count_segs); 102 return 0; 103 case MODULE_CMD_FINI: 104 MODULE_HOOK_UNSET(uvm_coredump_count_segs_hook); 105 MODULE_HOOK_UNSET(uvm_coredump_walkmap_hook); 106 #ifdef EXEC_ELF64 107 MODULE_HOOK_UNSET(coredump_elf64_hook); 108 #endif 109 #ifdef EXEC_ELF32 110 MODULE_HOOK_UNSET(coredump_elf32_hook); 111 #endif 112 MODULE_HOOK_UNSET(coredump_netbsd_hook); 113 MODULE_HOOK_UNSET(coredump_offset_hook); 114 MODULE_HOOK_UNSET(coredump_write_hook); 115 MODULE_HOOK_UNSET(coredump_hook); 116 return 0; 117 default: 118 return ENOTTY; 119 } 120 } 121 122 /* 123 * Dump core, into a file named "progname.core" or "core" (depending on the 124 * value of shortcorename), unless the process was setuid/setgid. 125 */ 126 static int 127 coredump(struct lwp *l, const char *pattern) 128 { 129 struct vnode *vp; 130 struct proc *p; 131 struct vmspace *vm; 132 kauth_cred_t cred; 133 struct pathbuf *pb; 134 struct nameidata nd; 135 struct vattr vattr; 136 struct coredump_iostate io; 137 struct plimit *lim; 138 int error, error1; 139 char *name, *lastslash; 140 141 name = PNBUF_GET(); 142 143 p = l->l_proc; 144 vm = p->p_vmspace; 145 146 mutex_enter(&proc_lock); /* p_session */ 147 mutex_enter(p->p_lock); 148 149 /* 150 * Refuse to core if the data + stack + user size is larger than 151 * the core dump limit. XXX THIS IS WRONG, because of mapped 152 * data. 153 */ 154 if (USPACE + ctob(vm->vm_dsize + vm->vm_ssize) >= 155 p->p_rlimit[RLIMIT_CORE].rlim_cur) { 156 error = EFBIG; /* better error code? */ 157 mutex_exit(p->p_lock); 158 mutex_exit(&proc_lock); 159 goto done; 160 } 161 162 /* 163 * It may well not be curproc, so grab a reference to its current 164 * credentials. 165 */ 166 kauth_cred_hold(p->p_cred); 167 cred = p->p_cred; 168 169 /* 170 * Make sure the process has not set-id, to prevent data leaks, 171 * unless it was specifically requested to allow set-id coredumps. 172 */ 173 if (p->p_flag & PK_SUGID) { 174 if (!security_setidcore_dump) { 175 error = EPERM; 176 mutex_exit(p->p_lock); 177 mutex_exit(&proc_lock); 178 goto done; 179 } 180 pattern = security_setidcore_path; 181 } 182 183 /* Lock, as p_limit and pl_corename might change. */ 184 lim = p->p_limit; 185 mutex_enter(&lim->pl_lock); 186 if (pattern == NULL) { 187 pattern = lim->pl_corename; 188 } 189 error = coredump_buildname(p, name, pattern, MAXPATHLEN); 190 mutex_exit(&lim->pl_lock); 191 192 if (error) { 193 mutex_exit(p->p_lock); 194 mutex_exit(&proc_lock); 195 goto done; 196 } 197 198 /* 199 * On a simple filename, see if the filesystem allow us to write 200 * core dumps there. 201 */ 202 lastslash = strrchr(name, '/'); 203 if (!lastslash) { 204 vp = p->p_cwdi->cwdi_cdir; 205 if (vp->v_mount == NULL || 206 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 207 error = EPERM; 208 } 209 210 mutex_exit(p->p_lock); 211 mutex_exit(&proc_lock); 212 if (error) 213 goto done; 214 215 /* 216 * On a complex filename, see if the filesystem allow us to write 217 * core dumps there. 218 * 219 * XXX: We should have an API that avoids double lookups 220 */ 221 if (lastslash) { 222 char c[2]; 223 224 if (lastslash - name >= MAXPATHLEN - 2) { 225 error = EPERM; 226 goto done; 227 } 228 229 c[0] = lastslash[1]; 230 c[1] = lastslash[2]; 231 lastslash[1] = '.'; 232 lastslash[2] = '\0'; 233 error = namei_simple_kernel(name, NSM_FOLLOW_NOEMULROOT, &vp); 234 if (error) 235 goto done; 236 if (vp->v_mount == NULL || 237 (vp->v_mount->mnt_flag & MNT_NOCOREDUMP) != 0) 238 error = EPERM; 239 vrele(vp); 240 if (error) 241 goto done; 242 lastslash[1] = c[0]; 243 lastslash[2] = c[1]; 244 } 245 246 pb = pathbuf_create(name); 247 if (pb == NULL) { 248 error = ENOMEM; 249 goto done; 250 } 251 NDINIT(&nd, LOOKUP, NOFOLLOW, pb); 252 if ((error = vn_open(&nd, O_CREAT | O_NOFOLLOW | FWRITE, 253 S_IRUSR | S_IWUSR)) != 0) { 254 pathbuf_destroy(pb); 255 goto done; 256 } 257 vp = nd.ni_vp; 258 pathbuf_destroy(pb); 259 260 /* 261 * Don't dump to: 262 * - non-regular files 263 * - files with links 264 * - files we don't own 265 */ 266 if (vp->v_type != VREG || 267 VOP_GETATTR(vp, &vattr, cred) || vattr.va_nlink != 1 || 268 vattr.va_uid != kauth_cred_geteuid(cred)) { 269 error = EACCES; 270 goto out; 271 } 272 vattr_null(&vattr); 273 vattr.va_size = 0; 274 275 if ((p->p_flag & PK_SUGID) && security_setidcore_dump) { 276 vattr.va_uid = security_setidcore_owner; 277 vattr.va_gid = security_setidcore_group; 278 vattr.va_mode = security_setidcore_mode; 279 } 280 281 VOP_SETATTR(vp, &vattr, cred); 282 p->p_acflag |= ACORE; 283 284 io.io_lwp = l; 285 io.io_vp = vp; 286 io.io_cred = cred; 287 io.io_offset = 0; 288 289 /* Now dump the actual core file. */ 290 error = (*p->p_execsw->es_coredump)(l, &io); 291 out: 292 VOP_UNLOCK(vp); 293 error1 = vn_close(vp, FWRITE, cred); 294 if (error == 0) 295 error = error1; 296 done: 297 if (name != NULL) 298 PNBUF_PUT(name); 299 return error; 300 } 301 302 static int 303 coredump_buildname(struct proc *p, char *dst, const char *src, size_t len) 304 { 305 const char *s; 306 char *d, *end; 307 int i; 308 309 KASSERT(mutex_owned(&proc_lock)); 310 311 for (s = src, d = dst, end = d + len; *s != '\0'; s++) { 312 if (*s == '%') { 313 switch (*(s + 1)) { 314 case 'n': 315 i = snprintf(d, end - d, "%s", p->p_comm); 316 break; 317 case 'p': 318 i = snprintf(d, end - d, "%d", p->p_pid); 319 break; 320 case 'u': 321 i = snprintf(d, end - d, "%.*s", 322 (int)sizeof p->p_pgrp->pg_session->s_login, 323 p->p_pgrp->pg_session->s_login); 324 break; 325 case 't': 326 i = snprintf(d, end - d, "%lld", 327 (long long)p->p_stats->p_start.tv_sec); 328 break; 329 default: 330 goto copy; 331 } 332 d += i; 333 s++; 334 } else { 335 copy: *d = *s; 336 d++; 337 } 338 if (d >= end) 339 return (ENAMETOOLONG); 340 } 341 *d = '\0'; 342 return 0; 343 } 344 345 static int 346 coredump_write(struct coredump_iostate *io, enum uio_seg segflg, 347 const void *data, size_t len) 348 { 349 int error; 350 351 error = vn_rdwr(UIO_WRITE, io->io_vp, __UNCONST(data), len, 352 io->io_offset, segflg, 353 IO_NODELOCKED|IO_UNIT, io->io_cred, NULL, 354 segflg == UIO_USERSPACE ? io->io_lwp : NULL); 355 if (error) { 356 printf("pid %d (%s): %s write of %zu@%p at %lld failed: %d\n", 357 io->io_lwp->l_proc->p_pid, io->io_lwp->l_proc->p_comm, 358 segflg == UIO_USERSPACE ? "user" : "system", 359 len, data, (long long) io->io_offset, error); 360 return (error); 361 } 362 363 io->io_offset += len; 364 return (0); 365 } 366 367 static off_t 368 coredump_offset(struct coredump_iostate *io) 369 { 370 return io->io_offset; 371 } 372
Indexes created Wed Sep 24 05:09:52 GMT 2025